Why So Cold? It’s the Stalled Jet Stream

Yes, we are having record cold snaps here in the East and Southeast. Global warming must be bunk then, right? Not so fast. Out West, its nice and toasty with unusually warm temperatures. Take a look at this map from the National Weather Service.

So why the big divide between East and West? Isn’t the temperature gradient between colder and warmer supposed to be more a North and South thing? Well, maybe once upon a time. Unfortunately, we are experiencing dramatic changes to the pattern of one of the biggest drivers of our climate on the North American Continent – the Jet Stream – and the rapid rate of the warming in the Arctic is the cause.

We are seeing single digit temperatures in the Carolinas while the Pacific Ocean along the West Coast is warmer than it should be this winter, where flowers are blooming in Washington state in February.

“Usually this time of the year in Seattle it’s dreary and drizzly, we’re pretty slow. But we’ve definitely been seeing a lot more inspiration in gardeners. Veggies are growing in the ground early. We’re seeing plums and cherries are already in full bloom,” said James Raebel, a landscape designer who works at the Magnolia Garden Center.

The big differences in temperature and snowfall across the country is a result of changes to the jet stream brought about by rapid Arctic warming. It’s explained in this report on the latest research from Phys.Org:

Rutgers University climate scientist Jennifer Francis and colleagues link that wavy jet stream to a warming Arctic, where climate changes near the top of the world are happening faster than in Earth’s middle latitudes.

A new study from Francis and University of Wisconsin-Madison scientist Stephen Vavrus, published in IOPscience, backs up that theory, with evidence linking regional and seasonal conditions in the Arctic to deeper north-south jet stream waves which will lead to more extreme weather across the country.

“The real story is how persistent the pattern has been. It’s been this way nearly continually since December 2013…Warm in the west, cold in the east,” Francis said. “We think with the warming Arctic these types of very wavy patterns, although probably not in the same locations, will happen more often in the future.”

Here’s what the research shows in a nutshell. As Arctic temperatures rise, it causes atmospheric changes to wind patterns that in the Northern hemisphere generally move from west to east, among them the jet stream that meanders across our continent. The Jet stream has always fluctuated over time, but those patterns have become more and more extreme since the 1990s, and in addition, frequently stalling for long periods of time, in effect locking in weather patterns both east and west. Here’s a more technical description of the effect:

The Arctic region has warmed more than twice as fast as the global average — a phenomenon known as Arctic amplification. The rapid Arctic warming has contributed to dramatic melting of Arctic sea ice and spring snow cover, at a pace greater than that simulated by climate models. These profound changes to the Arctic system have coincided with a period of ostensibly more frequent extreme weather events across the Northern Hemisphere mid-latitudes, including severe winters. The possibility of a link between Arctic change and mid-latitude weather has spurred research activities that reveal three potential dynamical pathways linking Arctic amplification to mid-latitude weather: changes in storm tracks, the jet stream, and planetary waves and their associated energy propagation. Through changes in these key atmospheric features, it is possible, in principle, for sea ice and snow cover to jointly influence mid-latitude weather.

The recent decade has seen an exceptional number of boreal summer weather extremes, some causing massive damage to society. There is a strong scientific debate about the underlying causes of these events. We show that high-amplitude quasi- stationary Rossby waves, associated with resonance circulation regimes, lead to persistent surface weather conditions and therefore to midlatitude synchronization of extreme heat and rainfall events. Since the onset of rapid Arctic amplification around 2000, a cluster of resonance circulation regimes is ob- served involving wave numbers 7 and 8. This has resulted in a statistically significant increase in the frequency of high- amplitude quasi-stationary waves with these wave numbers. Our findings provide important new insights regarding the link between Arctic changes and midlatitude extremes.

Again for the benefit of those who are not familiar with the science that supports these claims, lets turn to Greg Laden, a to put the jargon of the researchers in language even dolts such as myself can understand.

The CO2 by itself would warm the Earth to a certain degree, but it also produces what are called positive feedbacks. Which are not positive in a good way. For example, added CO2 means there is more water vapor in the atmosphere (because of more evaporation and ability for the atmosphere to hold water). Water vapor is, like CO2, a greenhouse gas. So we get even more warming. In the Arctic, there are a number of additional positive feedbacks that have to do with ice. The Arctic, with its additional positive feedbacks, warms more than other parts of the planet. This is called Arctic Amplification. […]

Normally, heat from the equator makes its way towards the poles via air and sea. Giant currents of air are set up by a combination of extra equatorial heat and the rotation of the earth. Part of this system is the so-called “trade winds” (winds that typically blow in a typical direction) and the jet streams. […]

But, with the warming of the Arctic, the differential between the equator and the poles is reduced, so all sorts of strange things happen, and one of those things is the formation of quasi-resonant Rossby waves.

A Rossby wave is simply a big giant meander in the jet stream. Quasi-resonant means “almost resonant” and resonant means that instead of the meanders meandering around, they sit in one place (almost). […]

In layperson’s terms, that means that the jet stream has moved significantly to the north out west, and has dipped down significantly to the south in the eastern United States, far more than what we’ve seen since records of the jet stream have been measured. Here’s Jennifer Francis, the research scientist and Professor at Rutgers with a Ph.D in Atmospheric Sciences, and co-author of the recent study with Stephen Vavrus of the study cited above, explaining the changes to the jet stream in a presentation she gave in 20l3:

Francis and Vavrus acknowledge criticism that their work is looking at relatively recent years since Arctic amplification emerged as a clear signal. Still, the researchers say there is no mistaking the trend since the 1990s: the Arctic probably hasn’t been this warm since the last major inter-glacial period 125,000 years ago.

Back then, Francis said, the Earth was several degrees warmer than now and sea levels were several meters higher. “The recent changes we’ve seen are clearly linked to increasing greenhouse gases, and there’s no sign of abatement in our use of fossil fuels. This does not bode well for impacts of extreme weather and the ecosystem as a whole,” she said.

Arctic amplification is going away. In fact it is increasing. By 2100, assuming we do not change our behavior, we will likely see an a temperature increase of “13°C in the Fall and 5 °C in the Spring, above pre-industrial levels.” That is equivalent to an increase of 23.4 degrees Fahrenheit in Fall and 9 degrees F in Spring, for those of us who are not familiar with using the Celsius scale. That’s an enormous change. If you think our weird weather is bad now, just wait and see what happens if we don’t start mitigating the effects of our carbon usage ASAP.

Imagine the storms, blizzards, floods, tornadoes, droughts and wildfires that will result. The pretty damn awful already, as we sit here in 2015. The cost of our continued reliance and use of fossil fuels for energy to power our homes, businesses and transportation, is literally going to be the death of us as a civilization and a society, at least one that anyone living today would recognize, or accept.

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